Joshua Siskin on the glories of coleus, how to propagate hydrangeas

tip of the week

Just when Michael Kappel, the heaven-sent gardener in our midst, had given up on his sweet autumn clematis (Clematis terniflora), God had other plans and it started to bloom. Several years ago, Kappel had planted this clematis at the base of some newly planted star jasmine (Tracehlospermum jasminoides) that were meant to grow into a vining screen along the side of his house. Now the jasmine are around 10 feet tall and, just a few weeks ago, Kappel’s clematis finally began to flower. Clematis are known for finding their way betwixt and between other plants and really do their best when protected on all sides by vegetation from other vines or tall shrubs. Sweet autumn clematis shows off large clusters of white, mildly fragrant flowers from now until fall. It is cold hardy and has no problem handling a hard frost.

I came upon some coleus. But not just any coleus, a glorious coleus. An overflowing profusion of color. Each leaf was a leaf within a leaf. Each primordial pink eruption surrounded by a heart-shaped field of burgundy-bronze. And, finally, a neatly toothed margin of green that framed each leaf around the edge.

You might think I was walking in a park, in a forest, or in some cloistered garden. But I was actually strolling on the sidewalk on the south side of Victory Boulevard, just east of Coldwater Canyon in North Hollywood. Not the most romantic setting for poetic musings, yet that’s where this coleus grew, in a planter outside an empty storefront office.

Plants do this all the time. They transform their surroundings. We take plants for granted but would be nothing without them. Just look around you. Los Angeles is a semi-arid zone, little more than an urban desert were it not for the plantscape that makes it green. In any city there is a strong emotional component to meetings between asphalt and vegetation, to encounters between concrete and coleus. No matter how dingy an urban corner may otherwise be, as long as a coleus is growing there, that corner will not be sad or bleak. Coleus is the candle that illuminates the darkness.

Permaculture

The best part of this job is that, while constantly on the look out for horticultural surprises, you never stop finding the most perfect horticultural displays in the most unlikely places. Plants are highly opportunistic. If you don’t pay attention, a seedling in the crack of a sidewalk or driveway can quickly turn into a palm, a fig, or a Brazilian pepper tree.

The Sepulveda Garden Center, located in Encino on Magnolia Boulevard between Hayvenhurst Avenue and Balboa Boulevard, is one of the best places not only for encountering botanical surprises but for learning horticultural lessons as well. While visiting the Center a few Sundays ago, I met Laurelle Johnson, who sang the praises of permaculture. Permaculture is a practice which, in its purest form, eliminates the need for any garden inputs other than what grows on site. Just add water and, presto, you have a garden that lasts forever. For instance, a permaculture vegetable garden would utilize leaves and stems of the plants growing there, once crops have been harvested, for mulch. You would grow heirloom vegetable varieties that breed true from seed so that the seeds for future squash or tomato plants would be extracted from the squash and tomatoes you harvest this year. Or, as Johnson has done, you would take slips or cuttings from an existing sweet potato plant and root them on site.

One of the classic procedures for building a compost pile involves alternate layering of organic material and soil. Johnson has created her planter beds by turning them into elongated compost piles. She has done this by alternating thin layers of garden debris, such as prunings and uprooted vegetable plants that have finished producing their crops with soil dug from between the beds. Where soil has been dug, pathways are now in place. Thus, permanent beds and permanent pathways between them have been developed with the same shovelfuls of earth.

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Johnson has an outstanding crop of butternut squash that appears almost ready for harvest. This is a type of winter squash, meaning it can be stored for months. Unlike other winter squash, which must be stored in a cool place, butternut squash can also be stored at room temperature and may be used in long-term table arrangements prior to consumption. Butternut squash is ready to harvest when its rind is thick enough to resist puncture by a fingernail.

Hydrangeas

“How do you propagate hydrangeas from cuttings and when should one do this? Also, when one purchases a certain color of this plant, how do we keep that color always. I have been told so many things but none have worked.”

— Shirley Schuhmacher, Rialto

Hydrangeas are among the easiest plants to propagate on account of their semi-succulent stems. Skilled propagators can even root hydrangea cuttings in water. For standard propagation, take 4- to 6-inch cuttings from stems that have yet to produce flowers. Retaining the top two leaves, remove leaves from bottom nodes (bumps where leaves meet stem). There should be around 2 inches of stem beneath bottom most node and cuttings should be inserted in rooting medium to a depth where this bottom node is covered. To speed rooting, cuttings may be dipped in root hormone prior to insertion in growing medium. Root hormone is available at nurseries but it is not required for rooting of hydrangea cuttings. You should also cut off the top half of hydrangea leaves to minimize water loss. Tenting of hydrangea cuttings with the aid of popsicle sticks and plastic wrap is also advised, although cuttings may root without being tented. Place them in bright light but away from hot sun and roots should start to form within three weeks. Rooting medium should be one part peat moss and one part perlite or sand.

As for retaining their color, blue hydrangeas demand highly acidic soil, which is achieved by fertilizing with aluminum sulfate on a regular basis. Pink and red hydrangeas will probably maintain their colors unassisted in our alkaline soil, but you may get more vivid color in them by fertilizing with super-phosphate. White hydrangeas do not change color. Incidentally, hydrangeas often turn green as they mature and may be harvested and utilized in dry arrangements when this color is shown. For unknown reasons, hydrangeas of any color may sometimes bloom in green for a year or two before reverting to their original color.